Fan blade retention system

ABSTRACT

A turbofan engine blade retainer for use in retaining a fan blade to a fan disk. The blade retainer includes a fore blade retainer for limiting forward movement of the fan blade and an aft blade retainer for limiting aft movement of the fan blade. The fore blade retainer engages a fore portion of the fan blade and the aft blade retainer engaging an aft portion of the fan blade.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional Patent Application No. 60/842,122 filed Sep. 1, 2006 and which is incorporated herein by reference.

FIELD OF THE INVENTION

The present inventions relates generally to fan blades in turbofan engines and more particularly, but not exclusively, to a fan blade retainer system for retaining a fan blade in a turbofan engine. Although, the present inventions were developed for use in turbofan engines, certain applications may be outside this field.

BACKGROUND

Presently many systems for attaching fan blades in a turbofan engine suffer from a number of disadvantages, limitations, and drawbacks including, for example, those respecting complexity of geometry, manufacturing cost, assembly time, local stress concentration in the attachment region, and fatigue life of the blade attachment. Thus, there is a continuing need for the development of technology for retaining fan blades within a turbofan engine. The present inventions satisfy this need in a novel and unobvious way.

SUMMARY

One form of the present invention contemplates a unique fan blade retainer for retaining fan blades within a turbofan engine. Other forms of the present invention contemplate unique apparatuses, systems, devices, hardware, methods, and combinations of these for defining a retainer for fan blades, compressor blades, and/or turbine blades. Further embodiments, forms, objects, features and aspects of the present inventions shall become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustrative schematic view of a gas turbine engine.

FIG. 2 is a partial cross-sectional view of a fan blade retention system according to an embodiment of the present invention.

FIG. 3 is an illustrative view of one embodiment of a retainer comprising a portion of one form of the present invention.

FIG. 4 is an illustrative view of another embodiment of a retainer comprising a portion of another form of the present invention.

FIG. 5 is an enlarged view of a portion of FIG. 2 comprising a tab portion interfaced with a disk lug.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of the inventions, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the inventions is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention is illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

Referring to FIG. 1, there is illustrated a schematic representation of an illustrative gas turbine engine 10, which includes a fan section 12, a compressor section 14, a combustor section 16, and a turbine section 18 that are integrated together to provide an aircraft flight propulsion engine. This type of gas turbine engine is generally referred to as a turbofan. A person of ordinary skill in the art should realize that there are multitudes of ways in which the gas turbine engine components can be linked together. The present invention is applicable to all types of turbofan engines and is not intended to be limited herein to an engine similar to that shown in the schematic of FIG. 1 unless specifically provided to the contrary. Further, the term aircraft is generic and includes, but is not limited to, helicopters, airplanes, missiles, unmanned space devices and any other substantially similar devices.

Compressor section 14 includes a rotor 20 having a plurality of compressor blades 22 coupled thereto. The rotor 20 is affixed to a shaft 24 that is rotatable within the gas turbine engine 10. A plurality of compressor vanes 26 are positioned within the compressor section 14 to direct the fluid flow relative to compressor blades 22. Turbine section 18 includes a plurality of turbine blades 28 that are coupled to a rotor disk 30. Rotor disk 30 is affixed to the shaft 24, which is rotatable within the gas turbine engine 10. Energy extracted in the turbine section 18 from the hot gas exiting the combustor section 16 is transmitted through shaft 24 to drive the compressor section 14. Further, a plurality of turbine vanes 32 are positioned within the turbine section 18 to direct the hot gaseous flow stream exiting the combustor section 16.

Turbine section 18 also provides power to a fan shaft 34, which drives the fan section 12. Fan section 12 includes a fan 36 having a plurality of fan blades 38 extending therefrom. Air enters the gas turbine engine 10 in the general direction of arrows A and passes through the fan section 12 into the compressor section 14 and a bypass duct 40. While the present disclosure will be with reference to a fan blade it is contemplated that forms of the present invention will be applicable to other gas turbine engine components including, but not limited to, compressor blades and turbine blades.

With reference to FIG. 2, there is illustrated a non-limiting cross-sectional view of a fan blade arrangement 41 including fan blade 38 coupled to fan disk 37. In one form the fan blade arrangement 41 is symmetrical about a centerline X. A person of ordinary skill in the art will recognize that there are a plurality of fan blades 38 coupled to fan disk 37. Fan disk 37 includes a fore face 42 and an aft face 44. Fan blade 38 includes an airfoil portion 50 and an attachment/root portion 52. The attachment/root portion 52 includes a fore face 56, an aft face 58, and a mechanical attachment portion, such as a dovetail or firtree. The mechanical attachment portion is located between portions of the fan disk 37 in a complementary slot 54 and functions to hold each of the plurality of fan blades in a radial position relative to the fan disk 37.

In one form of the present invention, a fore fan blade retainer 60 is provided at a first attachment region 57 for engaging fore face 56 and to limit movement of the plurality of fan blades 38 in a fore direction indicated by arrow 61. An aft blade retainer 62 is provided at a second attachment region 59 for engaging aft face 58 and to limit movement of the plurality of fan blades in an aft direction indicated by arrow 63.

The present invention contemplates, that fore blade retainer 60 is a member including a first portion 64 for engaging fore face 56 and a second portion 66 coupled to fore face 42 of fan disk 37. Fore blade retainer 60 is configured to retain a plurality of fan blades 38. The fore blade retainer 60 may be a single or multi-piece structure. In one form fan disk 37 includes an arm 70. In one form of the present invention the arm 70 is cylindrical and symmetrical about the axis X. In one form, second portion 66 is coupled to arm 70 of fan disk 37 with a plurality of circumferentially spaced fasteners 68. In one form, the fore blade retainer 60 is a thrust ring.

The aft blade retainer 62 includes a ring 72 and an aft plate 74. Ring 72 engages a portion of aft face 58 and is mounted within a circumferential ring slot 75 formed in fan disk 37. Aft plate 74 is coupled to the aft face 44 of fan disk 37. In one form the aft plate 74 is coupled to the fan disk 37 by a plurality of fasteners 84. In one form aft plate 74 includes an arm portion 80 that is coupled to a plurality of tabs 82 located atop of disk lug 71 by the plurality of fasteners 84. Referring to FIG. 5, there is illustrated an enlarged view of the tab 82 located about disk lug 71. In one form the fit between the tab 82 and the disk lug 71 is an interference fit. However, the present application is not limited to an interference fit between tab 82 and disk lug 71. In one form fan disk 37 includes a circumferential rail or portion 73 extending near the aft end of fan disk 37. In some forms of the invention, rail 73 extends continuously circumferentially around fan disk 37. However, rail 73 may be segmented and not extend completely circumferentially around the fan disk 37. In one form, rail 73 is scalloped in order to reduce overall weight of fan disk 37.

A pin 301 extending from ring 72 may be utilized with the ring for prevention of rotation of the ring. While the pin 301 has been illustrated in FIG. 3, it should be understood herein that a ring without the pin 301 is fully contemplated herein.

Ring 72 includes a first ring portion 76 positionable in ring slot 75. Ring 72 is positioned to engage aft face 58 to limit aft axial movement of the plurality of fan blades 38. Ring 72 may be a single or multi-piece structure. In one form, ring 72 is a split ring and may include a second portion 78 adapted to extend radially above rail 73. In one form of the present invention, second portion 78 of split ring 72 includes a relief portion (not shown) opposite the gap in the split ring for balancing purposes. With reference to FIG. 3, there is illustrated one form of split ring 72 including a portion 200. The relief portion 200 is disposed opposite the gap in the split ring, and in a preferred form is disposed opposite the gap in the split ring for balancing purposes.

With reference to FIG. 4, there is illustrated another embodiment of a ring 72′ utilized in the aft blade retainer 62 in place of ring 72. Ring 72′ is a multi-piece ring including a plurality of segments 300. Each of the segments 300 may include a pin 302 extending therefrom to prevent rotation and/or maintain equal spacing between the ring segments. While the pin 302 have been illustrated in FIG. 4, it should be understood herein that a ring 72′ without the pins 302 is fully contemplated herein. There are three equal sized segments illustrated, however the present application contemplates other number(s) of segments that may or may not be of equal size.

Aft plate 74 is adapted to engage at least a portion of the second ring portion 78 at an interface location 81. In one form the aft plate 74 engages second ring portion 78, and the centrifugal force of ring 72 is carried by aft plate 74. In one form, aft plate 74 is located within its self sustaining radius and therefore no radial load is transferred into the blade attachment. The centrifugal load on the aft plate 74 develops a hoop stress in the aft plate 74. Given the projected rotational speeds and maximum diameter of the aft plate 74, the hoop stress is significantly below the material allowable limit of applicable materials, such as but not limited to stainless steel, titanium, aluminum. As a result, the aft plate does not rely on the disk for support. It is noted that disk radial growth typically exceeds aft plate radial growth due to the relatively large blade and attachment dead load imposed on the disk.

In one form of the present invention, aft plate 74 covers aft face 44 of fan disk 37 and attachment region 59 and eliminates or minimizes windage off any interrupted portions in region(s) between platform 90 and disk rail 73 and prevents air leakage through this same area. An extension portion 86 of aft plate 74 is positioned to shield fan disk 37 from a flow of hot buffer air exiting a forward bearing compartment (not illustrated). Local stress concentration at region 75 is minimized since the circumferential slot does not disrupt the hoop stress field at the aft region of the disk. As a result, fatigue life capability of the blade attachment region is enhanced due to the reduction or elimination of local stress concentration at region 75.

In addition to the elimination or at least minimization of local stress concentration in the blade attachment region, the present invention also allows for a unique method of assembly. Assembly begins by inserting ring 72 into ring slot 75. Ring 72 would be expanded to allow it pass over rail 73 into ring slot 75. Once ring 72 is inserted into ring slot 75, aft plate 74 is slid over ring 72 and seated up against aft face 44 of fan disk 37. Chamfers (not shown) may be provided in aft plate 74 and aft side of second ring portion 78 to facilitate the seating of aft plate 74. Once seated, aft plate 74 would be coupled by the plurality of fasteners 84 to the fan disk 37. The attachment/root portion 52 of the plurality of fan blades 38 are inserted into the spaced complementary slots 54. Finally, fore blade retainer 60 is coupled to fan disk 37.

In addition to the unique method of assembly, the present invention also contemplates a method of accessing at least one of the plurality of fan blades 38 for repairing, removing, or inspecting at least one of the plurality of fan blades 38. The method of accessing requires only uncoupling fore blade retainer 60 from fan disk 37. Once fore blade retainer 60 is removed, access is provided for repair, removal, or inspection of at least one the plurality of fan blades 38.

One form of the present invention contemplates a gas turbine engine fan assembly, comprising: a fan disk having a fore face, an aft face, a complementary slot and a ring slot; a fan blade having an attachment portion including a fore root face and an aft root face, said attachment portion located within said complementary slot; a fore blade retainer engaging the fore root face to limit fore movement of the fan blade; and an aft blade retainer including a split ring, said split ring located in said ring slot and engaging said aft root face to limit aft movement of said fan blade.

The assembly of the present invention further contemplates the inclusion of an aft plate coupled to said aft face and retaining said split ring in the ring slot

The assembly of the present invention further contemplates that said fan disk includes a forwardly extending arm.

The assembly of the present invention further contemplates that said fore blade retainer is coupled to said forwardly extending arm.

The assembly of the present invention further contemplates that said fore blade retainer includes a first portion for engaging said fore root face and a second portion coupled to said fan disk.

The assembly of the present invention further contemplates that said second portion of said fore blade retainer is coupled to said fan disk by a plurality of fasteners.

The assembly of the present invention further contemplates that said split ring includes a first ring portion positioned in said ring slot and a second ring portion extending over a portion of said fan disk.

The assembly of the present invention further contemplates the inclusion of an aft plate coupled to said aft face and retaining said split ring in the complementary slot; and wherein said aft plate is adapted to engage said second ring portion and retain said first ring portion in said ring slot.

The assembly of the present invention further contemplates that said fan disk further includes a disk lug.

The assembly of the present invention further contemplates that said aft blade retainer is coupled to said disk lug.

The assembly of the present invention further contemplates that said fore blade retainer is a thrust ring.

The assembly of the present invention further contemplates that said fan disk includes a plurality of complementary slots; which further includes a plurality of said fan blades, each of said attachment portions located within one of said complementary slot; wherein said fore blade retainer engaging each of said fore root faces of said plurality of fan blades to limit fore movement thereof; and wherein said split ring engaging each of said aft root faces of said plurality of fan blades to limit aft movement thereof.

The assembly of the present invention further contemplates the inclusion of an aft plate coupled to said aft face and retaining said split ring in the complementary slot.

Another form of the present invention contemplates a fan blade assembly for a gas turbine engine comprising: a fan disk having a slot; a fan blade having a root portion disposed in said slot; and means for retaining said root portion in said slot.

Yet another form of the present invention contemplates a method of retaining a fan blade within a gas turbine engine fan disk, comprising: placing an attachment portion of the fan blade into a slot in a fan disk; engaging a fore face of the attachment portion with a fore blade retainer to retain fore movement of the fan blade in the slot; inserting a split ring into a circumferential slot in the fan disk, at least a portion of the split ring engaging an aft face of the attachment portion to retain aft movement of the fan blade in the slot; and coupling an aft plate to the fan disk, the aft plate engaging the split ring to retain the split ring in the circumferential slot.

The method of the present invention further contemplates coupling a portion of the fore blade retainer to a portion of the fan disk.

The method of the present invention further contemplates that the aft plate covers an aft face of the fan disk and the attachment region.

The method of the present invention further contemplates transferring a centrifugal load associated with the split ring to the aft plate.

The method of the present invention further contemplates shielding a portion of the disk and aft face of the attachment portion from windage.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary. 

1. A gas turbine engine fan assembly, comprising: a fan disk having a fore face, an aft face, a slot and a ring slot; a fan blade having an attachment portion including a fore root face and an aft root face, said attachment portion located within said slot; a fore blade retainer engageable with the fore root face to limit fore movement of the fan blade; and an aft blade retainer including a retainer, said retainer located in said ring slot and engageable with said aft root face to limit aft movement of said fan blade.
 2. The assembly of claim 1, wherein said retainer is a split ring.
 3. The assembly of claim 1, wherein said retainer is a multi-piece structure.
 4. The assembly of claim 1, which further includes an aft plate coupled to said aft face and retaining said split ring in the ring slot.
 5. The assembly of claim 1, wherein said fan disk includes a forwardly extending arm.
 6. The assembly of claim 5, wherein said fore blade retainer is coupled to said forwardly extending arm.
 7. The assembly of claim 1, wherein said fore blade retainer includes a first portion for engaging said fore root face and a second portion coupled to said fan disk.
 8. The assembly of claim 7, wherein said second portion of said fore blade retainer is coupled to said fan disk.
 9. The assembly of claim 1, wherein said retainer includes a first ring portion positioned in said ring slot and a second ring portion extending over a portion of said fan disk.
 10. The assembly of claim 9, which further includes an aft plate coupled to said aft face and retaining said retainer in the slot; wherein said retainer is a split ring; and wherein said aft plate is adapted to engage said second ring portion and retain said first ring portion in said ring slot.
 11. The assembly of claim 9, which further includes an aft plate coupled to said aft face and retaining said retainer in the slot; wherein said retainer is a multi-piece ring; and wherein said aft plate is adapted to engage said second ring portion and retain said first ring portion in said ring slot.
 12. The assembly of claim 1, wherein said fan disk includes a disk lug; and wherein said aft blade retainer is coupled to said disk lug.
 13. The assembly of claim 1, wherein said fore blade retainer is a thrust ring.
 14. A fan blade assembly for a gas turbine engine comprising: a fan disk having a slot; a fan blade having a root portion disposed in said slot; and means for retaining said root portion in said slot.
 15. The fan blade assembly of claim 14, wherein said means for retaining including a fore blade retainer for limiting fore movement of the fan blade; and an aft blade retainer including a ring disposed within a second slot in said fan disk for limiting aft movement of the fan blade.
 16. The fan blade assembly of claim 14, wherein said fan blade defines a plurality of fan blades, each of said plurality of fan blades having a root portion disposed in said slot; and said means for retaining maintaining each of said root portions in said slot.
 17. The fan blade assembly of claim 16, wherein said means for retaining including a fore blade retainer for limiting fore movement of the plurality of fan blade; and an aft blade retainer including a ring disposed within a second slot in said fan disk for limiting aft movement of the fan blades.
 18. The fan blade assembly of claim 16, wherein said ring is a multi-piece ring.
 19. A method of retaining a fan blade within a gas turbine engine fan disk, comprising: placing an attachment portion of the fan blade into a slot in a fan disk; engaging a fore face of the attachment portion with a fore blade retainer to retain fore movement of the fan blade in the slot; inserting a retainer ring into a circumferential slot in the fan disk, at least a portion of the retainer ring engaging an aft face of the attachment portion to retain aft movement of the fan blade in the slot; and coupling an aft plate to the fan disk, the aft plate engaging the retainer ring to retain the retainer ring in the circumferential slot.
 20. The method of claim 19, wherein said inserting includes placing the pieces from a multi-piece ring into the circumferential slot.
 21. The method of claim 19, wherein the retainer ring is a split ring.
 22. The method of claim 19, further comprising coupling a portion of the fore blade retainer to a portion of the fan disk.
 23. The method of claim 19, which further includes transferring a centrifugal load associated with the retainer ring to the aft plate.
 24. The method of claim 19, which further includes shielding a portion of the disk and aft face of the attachment portion from windage. 